Thursday, December 30, 2010

The most obvious external differences between the Grumman F8F -2 Bearcat in the lead picture above and the F8F-1 were the 12" taller vertical fin and rudder and the 20mm cannon armament (the latter was also a feature of the F8F-1B, the B suffix indicating a change in armament) indicated by the longer barrels and the bumps on the upper surface of the wing.

There was also a difference in the engine installation. Reportedly (see Davis Gandees comment below) only the first 23 "pre-production" F8F-1s had 5 exhaust stacks.

According to Gandees (and a subsequent comment by anonymous), the remaining F8F-1s had three exhaust stacks. The following sketch showing a fairing added to the trough to cover two lower stacks is is therefore incorrect.

The -1 shown here has the production exhaust trough with the lower side raised above the wing to smooth the flow over the wing and horizontal stabilizer.

This is the -2 trough with three exhaust pipes.

Air that had passed through the oil coolers was dumped through two "shutter" controlled doors between the inner main landing gear doors. These are the doors on the F8F-1:

Picture by Craig/J361 on Hyperscale

These doors were a slightly different configuration on the F8F-2. They were longer, extending farther forward, and had a scalloped cutout on the inboard side.

Picture by Ron Cline

A fixed oil cooler vent was also added across the bottom of the aft end of the -2 cowl (Mark Hayward picture from the Prime Portal F8F Walkaround):

Sunday, December 5, 2010

This is once again a work in progress, last updated on 6 December in the AM. I'm on the road so I don't have access to all my files. There may therefore be more errors and misstatements in the following than usual. Even then, it will pale beside the information available at Bob Jellison's website.

When the first pictures of the A3J-1 were published in Aviation Week, I thought it was the most beautiful airplane that I had ever seen. It was intended to replace the carrier-based, long-range atomic bomb delivery capability then provided by the Douglas A3D Skywarrior, except it was supersonic with a unique weapon delivery system. As it happened, only 59 were built, including the two prototypes, since it was the victim of a budget battle won by the proponents of the submarine-launched Polaris missile.

The nuclear bomb was carried internally but not dropped. Instead it was propelled rearward, attached to empty fuel tanks, out the back of the airplane at about 30 knots (not at the same speed as the aircraft as is frequently reported). Development of satisfactory accuracy of the bombing system was not achieved by the time it was apparent that Polaris was the better alternative for the requirement.

Before the bomber version was cancelled, however, the range of the Vigilante was to be improved with the A3J-2. Additional fuel was added by increasing the height of the fuselage over the wing and adding two additional external stores pylons. The extra weight was accommodated with a bigger wing and flaps and the addition of boundary layer control to the leading edge flaps. The engine inlet was also modified. Note that in the -2 prototype, the bleed air piping for the leading edge slats ran forward in the armpit of the wing.

The Navy ordered 18 -2s but only two were completed as such. The next four were built to aerodynamically represent a reconnaissance version, the A3J-3P, and used for transition training in the replacement air group squadron. (The leading edge BLC piping was relocated to above the wing and integrated with the overwing fairing.) The last 12 became the first RA-5Cs, the redesignation of the A3J-3P in November 1962.

These two pictures illustrate the difference in wing planform between the A3J-1 and the RA-5C.

If you look closely at the pictures (click on them first) you'll see two different positions of the unusual A3J/RA-5 lateral control system, one to roll left and the other to roll right. There were two sets of spoiler/slot/deflector controls on each wing, one to raise it and the other to lower it. The spoilers were hinged at the leading edge and the deflectors at the trailing edge to direct air flow through the slot.

All four sets were opened simultaneously to function as a speed brake.

The RA-5C was probably the best, certainly the most capable, reconnaissance airplane the Navy ever operated from carriers. It has never been replaced with anything comparable. It was fast, with good range/endurance, and big enough to carry an internal equipment pallet and a belly pod that could be fitted with cameras, side-looking radar, and electronic signal detectors. It retained the weapon delivery capability using the stores pylons but it is unlikely that it was ever used as an attack airplane, considering the RA-5C's value as a reconnaissance platform and that relatively few were assigned to each carrier air wing.

The nomenclature above is not precise in all cases since it is intended to differentiate between the various contracts, initial intentions, etc. Note that -3 is not a typo.

The 91 RA-5Cs built were augmented by conversions of earlier production. Not all sources agree, but Joe Baugher's website provides a list of conversions by BuNo. According to his tally, there were 43 A-5As converted including one of the A3J-1 prototypes. In addition, the first six of the original order of 18 A3J-2s were rebuilt to the RA-5C configuration, for a total fleet of 140. Some sources state 134, with the difference likely being the omission of the two A3J-2 prototypes and the four YA3J-3Ps. Of course, due to attrition (almost half of the A-5s built were destroyed in accidents and combat), the fleet never totaled 140 aircraft at any time. In fact, the production line was restarted, a very rare event, to build the last block of aircraft in order to bring the numbers back up to a satisfactory level.

The last new-build RA-5Cs were slightly different in addition to being powered by the J79-GE-10, which had a notably different afterburner nozzle.

The engine inlet of the last new-build aircraft had a different outboard shape, being straight instead of curved, and a small leading-edge extension was added along the side of the nacelle.

Early RA-5C inlet:

Late RA-5C inlet and leading edge extension:

There were, of course, detail changes over time to the ECM antennas, tail cone, etc. It also appears that some of the conversions from A-5As (and a couple of early build RA-5Cs) were to the later build inlet configuration with the leading-edge extension like BuNo 146702 shown here. Note that the RA-5C vertical fin tip slopes downward from front to back due to the addition of an IFF antenna.

From photographs, Craig Kaston has identified the following BuNos as receiving the late-build configuration: 146702, 149276, 149287, 149299, 149301, 150831, and 151630. Note that the last two were originally delivered as RA-5Cs in the early configuration.

Trumpeter has produced both 1/72nd and 1/48th kits of the RA-5C. It is reportedly a mix of features of the early and late configurations, but the major knock on the kit is the shape of the forward fuselage and vertical fin. For comparison, here are Rockwell drawings. (The first one shows the tip of the vertical fin as being roughly straight across, which is incorrect for almost all, if not all, of the RA-5Cs.)

About Me

In 1956, at age 12, I lived on NAS Sangley Point in the Philippine Islands. Always enamored with airplanes, I imprinted on the Cougars, Banshees, and Skyraiders then being deployed. Not able to be a Naval Aviator because I was nearsighted, I instead became an aeronautical engineer and general aviation pilot. Now retired, I write books and monographs on U.S. Navy aircraft.